Foamed articles such as flexible polyurethane foams are used as cushioning materials for products such as vehicle seats. At the bottom of such a foamed article, a reinforcing base fabric is provided in order to increase the rigidity of the urethane foam as well as to prevent the leakage of urethane to the backside. For example, this reinforcing base fabric is a combination of a Victoria lawn (cheesecloth) and urethane slab, or a worsted fabric. However, such base fabrics do not provide sufficient improvements in the rigidity of the urethane foams, or do not sufficiently prevent the leakage of urethane to the backside.
Various methods have been proposed to remedy these defects. For example, JP-Y-S62-26193 (Patent Document 1) discloses a nonwoven fabric as a reinforcing base fabric which is a combination of a thinner dense layer having a basis weight of 10 to 30 g/m2 and a bulky thick layer having a basis weight of 40 to 100 g/m2. JP-A-H02-258332 (Patent Document 2) discloses a high basis weight nonwoven fabric having a basis weight of 110 to 800 g/m2 and a fiber diameter of 1 to 16 d. JP-A-2004-353153 (Patent Document 3) discloses a reinforcing material which includes a dense layer that is a meltblown nonwoven fabric having a fiber diameter of not more than 10 μm.
With the foam-reinforcing base fabric disclosed in Patent Document 1, however, there is a risk that urethane leakage cannot be prevented effectively because the basis weight of the dense layer is low. Although the foam-reinforcing base fabric of Patent Document 2 can prevent urethane leakage, the basis weight of the base fabric is so large that the base fabric is impregnated with an excessively large amount of urethane, resulting in deteriorations in cushioning properties and strength due to lowering in urethane density, as well as in economic efficiency due to the large weight of the material.
Patent Document 3 describes that the dense layer may be a meltblown nonwoven fabric having a basis weight of 40 g/m2 or less, more preferably 15 to 20 g/m2, and a fiber diameter of not more than 10 μm. However, when the meltblown nonwoven fabric layer having such a small fiber diameter is needle punched to a spunbonded nonwoven fabric layer, the fibers of these layers are not entangled adequately probably because of a great difference in fiber diameter between the fibers forming the meltblown nonwoven fabric layer and the fibers forming the spunbonded nonwoven fabric layer. Thus, there is a risk that the layers are separated. Further, the needles can cut the fibers of the meltblown nonwoven fabric layer to cause the occurrence of fiber dust on the surface of the obtainable foam-reinforcing nonwoven fabric.